Abstract and Concrete Categories The Joy of Cats

by Jiri Adámek, Horst Herrlich, George E. Strecker

PREFACE to the ONLINE EDITION

Abstract and Concrete Categories was published by John Wiley and Sons, Inc, in 1990,
and after several reprints, the book has been sold out and unavailable for several years.
We now present an improved and corrected version as an open access file. This was made
possible due to the return of copyright to the authors, and due to many hours of hard
work and the exceptional skill of Christoph Schubert, to whom we wish to express our
profound gratitude. The illustrations of Edward Gorey are unfortunately missing in the
current version (for copyright reasons), but fortunately additional original illustrations
by Marcel Erné, to whom additional special thanks of the authors belong, counterbalance the loss.
Open access includes the right of any reader to copy, store or distribute the book or
parts of it freely. (See the GNU Free Documentation License at the end of the text.)
Besides the acknowledgements appearing at the end of the original preface (below),
we wish to thank all those who have helped to eliminate mistakes that survived the
first printing of the text, particularly H. Bargenda, J. Jürjens W. Meyer, L. Schröder A. M. Torkabud, and O. Wyler.
January 12, 2004